Industrial limit switches, such as global limit switches, safety interlocks, safety solenoid interlocks and cable pull limit switches, are used in a wide variety of industrial applications. Limit switches contain switches that are manufactured to suit the particular application.
U.S. Pat. No. 5,703,339 issue to Rapp et al describes a modern safety switch. The safety switch described by Rapp et al uses a key which, when inserted into and removed from a key channel, forcibly rotates a cam plate and thereby switches the position of the switch.
The prior safety switch further has an interlocking device for the cam plate which is disposed adjacent the latter, and can be forcibly released by the key when it is introduced into the key channel and has at least one locking member which can be displaced in translation and, in its locked position, engages in an interlocking manner with a housing disposed adjacent the cam plate. The locking member can be displaced into the released position by the key by means of an actuating which is moveable together with the locking member and is integral therewith. The part of the actuating member which projects into the key channel in the locked position is connected to the locking member by means of a material section which is laterally guided past the axis of rotation.
Despite interlocking in the prior art, it has been determined that more effective locking associated with safety switches is required where it is desirable that the locking mechanism prevent a key from being extracted outside of switch.